var x = 0,y = 0;
var div1 = document.getElementsByclassNameName("over")[0];
div1.addEventListener("mouseover",function(){
    var span = this.getElementsByTagName("span")[0];
    span.innerText = (x +=1);
},false);

var div2 = document.getElementsByclassNameName("enter")[0];
div2.addEventListener("mouseenter",function(){
    var span = this.getElementsByTagName("span")[0];
    span.innerText = (y +=1);
},false);
var a= 0,b = 0;
var div1 = document.getElementsByclassNameName("out")[0];
div1.addEventListener("mouseout",function(){
    var span = this.getElementsByTagName("span")[0];
    span.innerText = (a+=1);
},false);

var div2 = document.getElementsByclassNameName("leave")[0];
div2.addEventListener("mouseleave",function(){
    var span = this.getElementsByTagName("span")[0];
    span.innerText = (b +=1);
},false);